This invention relates generally to chromatography, and has particular reference to a novel apparatus and method for reducing interferences in chromatography.
The quantitation of components in a complex mixture by chromatography is frequently limited by the presence of interfering signals which are caused by components in the mixture having similar characteristics to components that are producing signals of interest. The problem is particularly accute when the complex mixtures are of biological or environmental origin, and elaborate clean-up and/or derivatization methods are often required for these analyses.
The applicants are not aware of any prior art that has addressed itself to the problem of reducing or minimizing interfering signals in chromatography through difference methods. The closest prior art known to the applicants is U.S. Pat. No. 3,847,550, issued Nov. 12, 1974 to Charles D. Scott et al. This patent is directed to a method of carrying out differential chromatography by simultaneously introducing samples into two parallel chromatographic columns, photometrically monitoring the outflow from the columns, electronically subtracting the output of one photometer from that of the other, and plotting the difference as a function of time. The present invention differs from that of the Scott et al patent in that it employs but a single column with two detectors and utilizes a variable volume cell in conjunction with one of the detectors, all as will be described hereinafter.
Other prior art, developed in the course of a preliminary search, consists of U.S. Pat. Nos. 3,223,747; 3,458,437; 3,486,304; 3,493,497; 3,508,880; 4,032,445; 4,043,906; 4,070,284; 4,128,476 and 4,137,161.